Orientation of OH bonds in kaolinite

INFRA-RED spectroscopy has been found to be a useful method in establishing the orientation of OH bonds in layer silicates1. In micas and related forms of crystallization, the orientation of the OH depends on the occupancy of the octahedral positions. In trioctahedral compositions, the OH bonds are normal to the flakes and these groups are free of association in any supplemental bond (absorption band at 3,700 cm.-1). In dioctahedral minerals, the OH are inclined about 20° to the plane of the flakes and directed to the unoccupied octahedra; the absorption band is observed at 3,620 cm.-1, which indicates some degree of secondary association. © 1962 Nature Publishing Group.Peer Reviewe